This invention relates to an accessory drive for an engine and more particularly to an improved arrangement for driving an accessory such as a high pressure fuel pump from one of the camshafts of an engine.
There have been proposed a variety of ways in which accessories are driven off of the engine and these drives are adapted, in part, to the specific accessory driven. One such engine driven accessory may comprise a high pressure fuel pump for supplying fuel to the charge forming system of an engine. Where direct cylinder injection is employed, this high pressure pump may a positive type pump that supplies the high pressure necessary for direct cylinder injection.
There is, obviously, an advantage in mounting the fuel pump in close location to the fuel injectors. This reduces the length and number of external conduits and avoids the possibility of pressure drops and leakage. In order to accomplish this, it has been proposed to drive the high pressure pump off of one end of one of the camshafts.
Of course, the camshaft is contained within a cam cover in a chamber that is defined by the cylinder head and the cam cover. This means that the pump drive must extend into the cam chamber for driving the pump and also that the pump body must be mounted on the exterior surface of the cylinder head assembly. Frequently, this involves either attaching bolts passing through both the cylinder head and the cam cover or only one of these arrangements. Because the cylinder head and the cam cover are not accurately aligned, for the most part, this provides a problem with insuring alignment of the fasteners. Furthermore, these types of mounting arrangements tend to provide an engine that has greater than desired overall length.
Also it is common to incorporate a housing at this end of the engine upon which the accessory is mounted. This housing includes the drive from the cam shaft to the accessory.
It is, therefore, a principal object of this invention to provide an improved camshaft driven engine accessory for an internal combustion engine.
It is a further object of this invention to provide an improved mounting and driving arrangement for the high pressure fuel pump of a fuel injected overhead cam engine.
It is a still further object of this invention to provide a mounting arrangement for the high pressure pump driven by a camshaft and which has a rigid and more accurately aligned mounting arrangement.